Enhanced Effluent Quality of Ceramic Membrane Ultrafiltration Combined with UV/TIO2 Photocatalysis

To decrease ratio of the organic compounds in permeate water during micro-polluted surface water ultrafiltration process, UV/TiO₂ photocatalytic oxidation was employed as ceramic membrane ultrafiltration (CMU) pretreatment by elevation of the level of effluent quality. Initially, the catalytic activity between new and recycled TiO₂ was estimated by the degradation of COD_Mn. The data illustrate that the photocatalytic efficiency exhibits no crucial distinction of activity between unused and used titanium dioxide after decomposition. Secondarily, the decomposition of organic matter was explored through UV/TiO₂-CMU cycling test. The results illuminate that the concentration of CODMn during the UV/TiO₂-CMU coupling technology is higher than the CMU technique. Conversely, the proportion of UV254 in the yield of UV/TiO₂-CMU is lower than CMU. This phenomenon is ascribed to the low molecular weight organic matter, which is formed from macromolecule organic matter under incomplete photocatalytic dissociation. This micromolecule substance can easily penetrate membrane pores incurring the rising of COD_Mn in UV/TiO₂-CMU hybrid system. Concurrently, this intermediate product is insensitive to ultraviolet light, diminishing the content of UV₂₅₄. Subsequently, parameters such as the reflux ratio, concentration of TiO₂, aeration rate, transmembrane pressure, and crossflow velocity that affected water quality in the hybrid process were investigated by single-factor experiments. Meanwhile, the main variables were optimized by orthogonal methodology using the removal of CO_DMn as the response value. Optimal outcomes are attained at a reflux ratio of 85%, 0.5 g/L additional TiO₂, an aeration rate of 5 L/min, a transmembrane pressure of 0.05 MPa, and a crossflow velocity of 1.0 m/s.